Yield, chemical composition, in vitro digestibility and kinetics of fermentation of straw from 18 varieties of oats (Avena sativa L.) were studied. All the straw varieties were grown in three replicates under the same agronomic conditions. Significance differences were observed in the yield of straw (4.4 to 7.5 ton dry matter (DM)/ha) from different varieties. The proportion of seed/straw from these varieties varied from 0.28 to 1.02. Crude protein (CP), neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL) content varied from 24.2 to 48.1, 626 to 708, 437 to 533 and 52.0 to 92.4 g/kg DM, respectively in the straws. In vitro organic matter digestibility (IVOMD) differed among varieties and varied from 400 to 539 g/kg DM. The mean value of digestible organic matter yield (DOM) was 2.34 ton/ha. A significant difference was observed in the potential gas production (A) and lag time (L) among varieties. The fractional rate of gas production (c, /h) ranged from 0.030 to 0.034. The results emphasized that in any evaluation of oat varieties, kinetics of digestion or fermentation should be taken into consideration as well as yield and digestibility.